Digitizers, also known as graphic tablets, are computer peripherals used to manually input graphic information with an electronic pen or cursor. The size of digitizers are normally ranked as small, medium, and large format. Large format digitizers, with active areas typically ranging from 24".times.36" to 44".times.60", as (10 in FIG. 1) are usually supported by a table 12 as depicted in FIG. 1 or a pedestal 13 as depicted in FIG. 2, and are used in either horizontal or inclined position. These support arrangements work well for digitizer applications that use paper drawings such as construction cost estimating, map or image analysis or computer-aided design. Computerized meeting systems is a new application for large format digitizers. The digitizer in this application is sometimes referred to as a digital whiteboard. When used as a digital whiteboard, the digitizer must be mounted vertically, as shown in FIG. 3, so that the meeting participants can easily view the information that has been either projected and/or hand written on the digitizer with special electronic markers.
The design of a vertical-mounting stand for a rigid digital whiteboard, as depicted in FIG. 3, is relatively straightforward. In this design two inverted "T" legs 30 are fabricated from tubular steel and have casters 34 attached at the bottom of each leg. A horizontal cross member 32 provides rotational stiffness for the "T" legs. The inverted "T" legs are attached to an edge extrusion 14 of the digitizer. This arrangement results in a freestanding, self-supporting horizontally stiff, vertically mounted digitizer that can be rolled from place to place. This support arrangement is easily modified for various digitizer designs, and is very similar to support stands used for many types of mobile whiteboards, blackboards, message boards, etc. Standard whiteboards have been designed to provide the minimum amount of required horizontal stiffness to maintain a stable writing surface. However, even with a minimum-stiffness design, the weight of typical stand is approximately 25 pounds. This along with the weight of the whiteboard itself results in an arrangement that may be acceptable for fixed location use, but does not lend itself for portable applications.
Another type of digital whiteboard uses a lightweight, flexible digitizer. The lightweight and flexible nature of the design allows for easy transport either within an office building or to remote sites. Since this digitizer does not have any inherent stiffness, as do standard large format rigid digital whiteboards, it must be fully supported across its surface. A portable stand of the type used for a rigid digitizer would have to have a supporting structure for the tablet's surface. This support structure would have to be made of a relatively stiff material, such as wood or plastic. The high weight of the inverted "T" leg stand in conjunction with the weight of the tablet support structure for the flexible tablet makes the standard vertical stand design unsuitable for portable use. One of the design requirements that adds significantly to the weight of the inverted "T" leg stand design is that it be self supporting. When a user applies a force against the surface of the digitizer supported by the stand, as occurs during writing, the surface of the digitizer must remain relatively stationary. Any perceptible movement of the digital whiteboard surface would make it difficult for the user to write clearly. Consequently, a trade-off is made; additional weight in the overall support structure for the digitizer in exchange for a stable writing surface. The conventional art does not provide an arrangement that allows a stable writing surface for a digitizer while requiring only the minimal weight for the overall digitizer and support stand arrangement.